Ultralow-temperature cutting machining method and clamp for shaped charge liner part

Abstract

The invention discloses an ultralow-temperature cutting machining method for a shaped charge liner part and a clamp. The ultralow-temperature cutting machining method comprises the steps that a machine tool spindle is connected into a pipeline, a-198 DEG C liquid nitrogen coolant or a-78 DEG C liquid carbon dioxide coolant is introduced into the clamp, and the shaped charge liner part is cooled. According to the clamp, after the bottom face of a shaped charge liner is subjected to finish machining and the outer circle end face is subjected to semi-finish machining, a set of cutting combined clamp is adopted, and after the outer convex arc face of the shaped charge liner part is subjected to finish machining and a reaming hole is subjected to finish machining, the relative position of a clamp body on a machine tool is kept unchanged, and the part is turned over; therefore, the inner concave cambered surface of the shaped charge liner part can be finely machined. According to the fixture, one fixture main body is shared when the outer convex cambered surface and the inner concave cambered surface of the shaped charge liner are subjected to finish machining, so that the required special cutting fixture is reduced, the auxiliary machining time is shortened, the machining efficiency and the machining precision of shaped charge liner parts are improved, and high-efficiency and high-quality machining is realized.

Description

Technical Field

[0001] The invention relates to the technical field of mechanical processing, and in particular to an ultra-low temperature cutting processing method and a fixture for a medicine liner part. Background Art

[0002] like Figure 1 As shown, Figure 1 This is a schematic diagram of the structure of a tantalum-tungsten alloy charge liner part. The specific features include an outer convex arc surface, a bevel, an outer cylindrical end surface, a bottom surface, an inner concave arc surface, and a center hole. Charge liner parts are typical thin-walled feature parts, which are prone to deformation during processing. Therefore, it is necessary to design a special fixture during the cutting process and strictly formulate the corresponding mechanical processing process regulations to reduce the deformation during the processing and ensure dimensional accuracy.

[0003] Tantalum-tungsten alloy has high plasticity and hardness. Under traditional pouring cutting conditions, there will be processing problems such as high cutting force, high cutting heat, severe tool sticking, and low tool life. Therefore, it is necessary to carry out cutting under liquid nitrogen or liquid carbon dioxide cooling conditions to reduce the temperature of the cutting area, delay the tool wear process, and increase the tool life, so as to increase the number of parts that can be cut by each tool.

[0004] In addition, the existing processing methods require the design and manufacture of special cutting fixtures when finishing the outer convex and inner concave surfaces of the liner parts, which increases the production and manufacturing costs. The repeated positioning of the fixture not only increases the auxiliary processing time required during the processing, making the processing efficiency low, but also increases human errors and affects the processing accuracy.

[0005] Therefore, reducing the cutting heat generated during the cutting process, increasing the service life of the tool, reducing the number of special cutting fixtures used, shortening the auxiliary processing time, and improving the processing accuracy are technical issues that need to be urgently solved to improve processing efficiency and product quality. Summary of the invention

[0006] The present invention provides a method and a fixture for ultra-low temperature cutting of a liner part, which are used to address the above-mentioned shortcomings in the prior art and achieve the use of the same fixture body when fine-machining the outer convex curved surface and the inner concave curved surface of the liner part in an ultra-low temperature cooling environment of liquid nitrogen or liquid carbon dioxide, so as to reduce the number of special cutting fixtures used and achieve the purpose of improving processing efficiency and product quality.

[0007] The present invention is achieved through the following technical solutions:

[0008] A liner part cutting fixture, comprising:

[0009] Cylindrical roller bearings;

[0010] A fixture body sleeved on the cylindrical roller bearing, wherein the cylindrical roller bearing and the fixture body are interference fit;

[0011] a pipe disposed inside the cylindrical roller bearing;

[0012] An outer convex arc surface clamping piece and an inner concave arc surface clamping piece are connected to the end of the clamp body through threads and are used to clamp the medicine-shaped liner parts;

[0013] A fixture core that is clearance-matched with the fixture body, wherein the fixture core has a concave surface that is consistent with the convex arc surface of the finely machined liner part;

[0014] The fixture core has a groove, which can allow liquid nitrogen or liquid carbon dioxide to enter the surface of the liner part to cool the liner part when finishing the inner concave surface of the liner part.

[0015] The medicine-shaped cover part comprises: a shell with an opening at one end.

[0016] The present invention uses a common fixture body when finishing the outer convex arc surface and the inner concave arc surface of the liner, thereby reducing the required special cutting fixtures and shortening the auxiliary processing time. In addition, during the cutting process, directly cooling the liner parts with liquid nitrogen or liquid carbon dioxide coolant can effectively reduce the cutting heat generated during the cutting process, inhibit the generation of built-up edge, and increase the service life of the tool, which is conducive to improving the processing efficiency and processing accuracy of the liner parts and achieving efficient and high-quality processing thereof.

[0017] A method for ultra-low temperature cutting of a liner part, using the liner part cutting fixture, comprises the following steps:

[0018] The liner parts to be processed are fixed by a liner parts cutting fixture, and the convex and concave surfaces are finely processed under the cooling conditions of liquid nitrogen or liquid carbon dioxide.

[0019] The liner parts to be processed are fixed by using the liner parts cutting and processing fixture, specifically including:

[0020] Step 1: Install the cylindrical roller bearing inside the fixture body;

[0021] Step 2: Fix the fixture body on the machine tool;

[0022] Step 3: Connect liquid nitrogen or liquid carbon dioxide to the inside of the fixture body through a pipeline to directly cool the liner parts;

[0023] Step 4: Use an outer convex curved surface clamp to install the outer convex curved surface of the liner part to be processed on the working side of the processing tool;

[0024] Step 5: Finely process the convex arc surface of the liner parts and finely ream the holes;

[0025] Step 6: Install the fixture core;

[0026] Step 7: Use the concave arc surface clamping piece to install the concave arc surface of the liner part to be processed on the working side of the processing tool;

[0027] Step 8: Finish the concave arc surface of the liner part.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The present invention aims to solve the problems of severe tool wear and low processing efficiency when finishing the outer convex and inner concave surfaces of tantalum-tungsten alloy charge liner parts under traditional casting cutting conditions, and proposes a method and fixture for ultra-low temperature cutting of charge liner parts. The ultra-low temperature cutting method includes connecting a cryogenic pipeline through a machine tool spindle, introducing liquid nitrogen or liquid carbon dioxide coolant into the interior of the fixture, and cooling the charge liner parts to reduce the cutting heat generated during the machining process, inhibit the formation of built-up edge, and increase the tool life. The fixture includes a set of special cutting combined fixtures after finishing the bottom surface and semi-finishing the outer cylindrical end surface. By replacing different clamping parts and adding fixture cores, the charge liner parts are turned over after finishing the outer convex surface and fine reaming, so as to finish the inner concave surface of the charge liner. The auxiliary processing time caused by repeated positioning of the fixture body is shortened, which is conducive to improving processing efficiency and product quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention, but do not constitute a limitation of the present invention.

[0031] Figure 1 It is a schematic diagram of the structure of the liner parts.

[0032] Figure 2 This is the processing flow chart of the liner parts.

[0033] Figure 3 It is a flow chart of the present invention.

[0034] Figure 4 This is an isometric diagram of the structure of several common liner parts.

[0035] Figure 5 This is a full cross-sectional view of the structure of several common liner parts.

[0036] Figure 6 This is a schematic diagram of the clamping when finishing the convex curved surface and fine boring.

[0037] Figure 7This is a schematic diagram of the clamping when finishing the concave arc surface. DETAILED DESCRIPTION

[0038] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiment of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without creative work should fall within the scope of protection of the present invention.

[0039] Figure 1 This is a schematic diagram of the structure of the tantalum-tungsten alloy charge liner. The specific features include the outer convex arc surface, the inclined surface, the outer cylindrical end surface, the bottom surface, the inner concave arc surface and the center hole. Tantalum-tungsten alloy has high plasticity and hardness. Under the traditional casting cutting conditions, there will be problems such as large cutting force, high cutting heat, and the formation of built-up edge in the cutting processing area, which will lead to low tool life and poor surface quality.

[0040] Figure 2 This is a flow chart for the processing of liner parts, which specifically includes the following steps:

[0041] 1. Select the blank after forging and annealing as the workpiece to be processed;

[0042] 2. Drill the center hole to Rough reaming of center hole to The surface roughness after rough reaming of the center hole should not be greater than 3.2μm;

[0043] 3. Rough turning of the outer end surface The height from the rough-machined bottom surface to the part is 22.5mm. The surface roughness of the outer cylindrical end surface and the bottom plane of the rough-machined liner part should not be greater than 3.2μm, and the coaxiality requirement between the center hole and the outer cylindrical end surface should not be greater than The flatness requirement of the bottom plane should not be greater than 0.04mm, and the verticality requirement between the center hole and the bottom surface should not be greater than 0.04mm;

[0044] 4. Roughly process the convex arc surface, remove the excess 0.4mm, and the surface roughness of the convex arc surface of the liner part after rough processing should not be greater than 3.2μm;

[0045] 5. Roughly process the inner concave surface, remove the excess of 0.4mm, and the surface roughness of the inner concave surface of the liner part after rough processing should not be greater than 3.2μm;

[0046] 6. Semi-finishing of the outer cylindrical end surface The bottom surface should be finished to a height of 21.5 mm. The surface roughness of the semi-finished outer end surface of the liner should not be greater than 1.6 μm. The surface roughness of the bottom plane of the liner should not be greater than 1.6 μm. The coaxiality requirement between the center hole and the outer end surface should not be greater than The flatness requirement of the bottom plane should not be greater than 0.02mm, and the verticality requirement between the center hole and the bottom surface should not be greater than 0.02mm;

[0047] 7. Finish the outer convex arc surface, remove the excess 0.1mm, and finely ream the hole to The surface roughness of the convex arc surface and the fine reaming of the liner parts should not exceed 1.6μm. After the center hole is finely reamed, the coaxiality requirement between the center hole and the outer cylindrical end surface should not exceed The verticality requirement between the center hole and the bottom surface should not be greater than 0.02mm;

[0048] 8. Finish the inner concave surface, remove the excess 0.1mm, and the surface roughness of the inner concave surface of the liner part after finishing should not be greater than 1.6μm;

[0049] 9. Finish machining of the outer cylindrical end surface After the parts are processed, in addition to the corresponding dimensional accuracy, the surface roughness of the parts should not exceed 1.6μm, and the coaxiality requirements of the center hole and the outer cylindrical end face should not exceed The verticality requirement between the center hole and the bottom surface should not be greater than 0.02mm;

[0050] 10. Remove the parts, rinse them with water, and inspect the surface defects, dimensional accuracy, geometric accuracy and surface roughness of the parts according to national standards to see if they meet the requirements. If correct, pack them and put them into storage.

[0051] Figure 3 The flowchart of the fine processing of the outer convex arc surface and the inner concave arc surface of the medicine liner part according to the present invention specifically includes the following steps:

[0052] 1. Install cylindrical roller bearing 1

[0053] The center hole of the fixture body 2 is locally heated, and the cylindrical roller bearing 1 is axially positioned by the shaft shoulder of the center hole of the fixture body 2;

[0054] 2. Install the fixture body 2

[0055] Fix the assembly of the cylindrical roller bearing 1 and the fixture body 2 on the machine tool with a three-jaw chuck, and check whether the coaxiality of the center hole of the fixture body 2 matched with the fixture core 5 and the hole matched with the outer cylindrical end surface of the medicine liner part meets the requirements, and whether the flatness of the top plane of the fixture body 2 meets the requirements;

[0056] 3. Connect pipeline 3

[0057] Through the machine tool spindle, -198°C liquid nitrogen or -78°C liquid carbon dioxide coolant is introduced into the fixture through pipeline 3 to directly cool the liner parts;

[0058] 4. Clamp the parts to be processed

[0059] Make the bottom surface of the finely machined liner part fit the plane of the top of the fixture body 2, and use the inclined surface of the convex arc clamping piece 4 to press the liner part tightly;

[0060] 5. Fine machining of the convex surface of the liner parts

[0061] After installation, the outer convex surface of the liner parts is precisely cut under the cooling conditions of -198℃ liquid nitrogen or -78℃ liquid carbon dioxide, and the excess is removed by 0.1mm;

[0062] 6. Precision reaming of the center hole

[0063] Under the cooling conditions of -198℃ liquid nitrogen or -78℃ liquid carbon dioxide, the hole is finely reamed to

[0064] 7. Install the fixture core 5

[0065] Keep the relative position of the fixture body 2 on the machine tool unchanged, install the fixture core 5, and after the installation is completed, check whether the coaxiality requirement of the center hole of the fixture core 5 meets the requirement;

[0066] 8. Clamp the parts to be processed

[0067] Turn the part over so that the convex arc surface of the medicine liner part fits the concave surface of the clamp core, and position it through a cylindrical pin, and use the concave arc surface clamp 6 to press the bottom surface of the medicine liner part;

[0068] 9. Fine machining of the concave surface of the liner

[0069] After installation, the convex surface of the liner parts is precisely cut under the cooling conditions of -198℃ liquid nitrogen or -78℃ liquid carbon dioxide, removing 0.1mm of excess.

[0070] Figure 4 and Figure 5 They are isometric schematic diagrams and full cross-sectional views of several common liner parts structures, including disc-shaped liner, single-conical liner, double-conical liner, trumpet-shaped liner, trumpet-conical angle combined liner, and bell-shaped liner.

[0071] When finishing the convex curved surface of different charge liner parts, the parts can be positioned by the outer circular end surface. When finishing the concave curved surface of different charge liner parts, the convex curved surface after finishing can be used for positioning. In this way, one fixture body can be shared when finishing the convex curved surface and the concave curved surface, thereby reducing the design and manufacture of special cutting fixtures and achieving efficient and rapid positioning of the workpiece to be processed.

[0072] Figure 6 The schematic diagram of the clamping device for fine machining of an outer convex arc surface and fine reaming of a hole mainly includes a cylindrical roller bearing 1, a clamp body 2 sleeved on the cylindrical roller bearing 1, a pipe 3 arranged in the cylindrical roller bearing 1, and an outer convex arc surface clamping member 4.

[0073] The coaxiality requirement of the hole of the clamp body 2 that matches the clearance of the clamp core 5, the hole that matches the transition of the outer cylindrical end surface of the medicine liner, and the shaft segment clamped by the three-jaw chuck should be no greater than The flatness requirement of the top plane should be no greater than 0.04mm, the verticality requirement of the hole that transitions with the outer cylindrical end face of the liner and the bottom surface should be no greater than 0.04mm, and the surface roughness of the hole of the fixture body 2 that matches the clearance of the fixture core 5, the hole that transitions with the outer cylindrical end face of the liner, the shaft section clamped by the three-jaw chuck, and the top plane should be no greater than 1.6μm;

[0074] When finishing the convex curved surface and fine reaming, -198℃ liquid nitrogen or -78℃ liquid carbon dioxide low-temperature coolant is introduced into the fixture through pipeline 3 to cool the liner part. The fixture body 2 is fixed to the machine tool with a three-jaw chuck, and the inclined surface of the liner part is clamped by the convex curved surface clamping piece 4, thereby realizing the processing and positioning of the convex curved surface of the liner part in an ultra-low temperature environment.

[0075] Figure 7 The schematic diagram of the clamping for finishing the inner concave arc surface mainly includes a cylindrical roller bearing 1, a clamp body 2 sleeved on the cylindrical roller bearing 1, a pipe 3 arranged in the cylindrical roller bearing 1, a clamp core 5 with a clearance fit with the center hole of the clamp body 2, and a concave arc surface clamping piece 4.

[0076] The coaxiality requirement of the center hole for positioning of the clamp core 5 and the axis of the clamp body 2 should not be greater than The contour of the concave surface matching the outer convex arc surface should be no greater than 0.04 mm, and the surface roughness of the axis, concave surface and center hole of the clamp core 5 matching the clamp body 2 should be no greater than 1.6 μm.

[0077] When finishing the inner concave arc surface, keep the relative positions of the cylindrical roller bearing 1, the fixture body 2 and the pipe 3 on the machine tool unchanged, insert the fixture core 5 into the center hole of the fixture body 2, make the finished convex arc surface fit the concave surface of the fixture core 5, and use a cylindrical pin to position it, and clamp the bottom surface of the charge liner through the inner concave arc surface clamping piece 6, so as to realize the processing and positioning of the inner concave arc surface of the charge liner part in an ultra-low temperature environment.

[0078] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A liner parts cutting fixture, characterized in that: include: Cylindrical roller bearing (1); A fixture body (2), the cylindrical roller bearing (1) being sleeved on the fixture body (2), and the cylindrical roller bearing (1) and the fixture body (2) being interference fit; A pipeline (3), wherein the pipeline (3) is arranged in the cylindrical roller bearing (1); A liner clamping piece, the clamping piece cooperates with the end of the clamp body (2) to clamp the liner parts; A clamp core (5), wherein the clamp core (5) is clearance-matched with the clamp body (2).

2. The liner parts cutting fixture according to claim 1 is characterized in that: The medicine-shaped cover part comprises: a shell with an opening at one end.

3. The liner parts cutting fixture according to claim 1 is characterized in that: The medicine-shaped liner component comprises: an arc-shaped body, an outer convex arc surface and an inner concave arc surface.

4. The liner parts cutting fixture according to claim 3 is characterized in that: The medicine liner clamping piece is an outwardly convex arc surface clamping piece (4), which is installed on the end of the clamp body (2) through a threaded connection, and the end of the outwardly convex arc surface clamping piece (4) is provided with an arc surface that cooperates and presses with the outwardly convex arc surface of the medicine liner part.

5. The liner parts cutting fixture according to claim 3 is characterized in that: The medicine liner clamping piece is a concave arc surface clamping piece (6), which is installed on the end of the clamp body (2) through a threaded connection, and the end of the concave arc surface clamping piece (6) is provided with a flat surface that cooperates and presses with the bottom plane of the medicine liner part.

6. The liner parts cutting fixture according to claim 5, characterized in that: A clamp core (5) is installed in the clamp body (2) and matches the outer convex curved surface of the medicine liner part.

7. The liner parts cutting fixture according to claim 6, characterized in that: The clamp core (5) is provided with a groove for gas to pass through.

8. A method for ultra-low temperature cutting of liner parts, characterized in that: Using the liner parts cutting and processing fixture according to any one of claims 1 to 7, The following steps are involved: The liner parts to be processed are fixed by a liner parts cutting fixture, and the convex and concave surfaces are finely processed under the cooling conditions of liquid nitrogen or liquid carbon dioxide.

9. The ultra-low temperature cutting method for liner parts according to claim 8, characterized in that: The liner parts to be processed are fixed by using the liner parts cutting and processing fixture, specifically including: Step 1: Install the cylindrical roller bearing (1) inside the fixture body (2); Step 2: Fix the fixture body (2) on the machine tool; Step 3: Liquid nitrogen or liquid carbon dioxide is connected to the inside of the fixture body (2) through a pipeline (3) to directly cool the liner parts; Step 4: Using the convex curved surface clamping piece (4), the convex curved surface of the liner part to be processed is mounted on the working side of the processing tool; Step 5: Finishing the convex arc surface of the liner parts; Step 6: Install the fixture core (5); Step 7: Using the concave arc surface clamping piece (6), the concave arc surface of the liner part to be processed is installed on the working side of the processing tool; Step 8: Finish the concave arc surface of the liner part.

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